Modern communications demand higher data rates and performance. Multiple input, multiple output (MIMO) antenna systems, also known as multiple-element antenna (MEA) systems, achieve greater spectral efficiency for allocated radio frequency (RF) channel bandwidths by utilizing space or antenna diversity at both the transmitter and the receiver.
MIMO receivers typically include fixed pulse-shaping filters such as, for example, root-raised cosine (RRC) or finite impulse response (FIR) filters. Such filters are designed to provide most of the channel-selection filtering in the digital domain. Thus, such filters eliminate the need for an intermediate frequency (IF) stage, but increase inter-chip interference (ICI) for low selectivity.
There is therefore a need for efficient receiver filters for use in MIMO systems. More particularly, there is a need for reconfigurable digital filters for MIMO receivers that reduce processing power and power dissipation for multiple MIMO streams.